Fan



Dec. 17, 1940. I E, ANbERsoN v 2,225,406

FAN

' Original Filed April 13, 1936 2 Sheets-Sheet 1 INVEN'I 'OR ATTORNEY L AND ERSbN 2, 2 5

Dec. 17;, 1940.

2 Sheets-Sheet 2 Original Filed April 13, 1936 INVENTOR I Q A. M ATTORNEY M232 N. .on 3 o a 3 d 8 s I 2 3 02 Q a M I: am

Patented Dec. 11, 1940 UNITED STATES ran Edward Lowell Anderson, Grosse Isle, Mich, as-

signor to American Blower Corporation, Detroit, Micln, a corporation of Delaware Original 14,119.

application Apr-i113, 1930, serial No. Divided and this application February 7, 1938, Serial No. 189,092

9 Claims.

of back suction between the fan blades and the fan ring sons to materially increase the range of air volumes which can be efficiently handled by the fan.

Another object is to provide a fan having an exceedingly low noise pitch.

Another object is to provide a fan inwhich the direction of the discharging air may be reversed by reversal of rotation 01 the fan blades without impairing the efllciency of the fan.

The invention consists in the novel construction of the fan and the cooperative relation between the fan blades and the fan ring, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed;

In the accompanying drawings, to be taken as apart oi this specification, I have fully and clearly illustrated certain ian structures embodying my invention, in which drawings- Figure 1 is a view in vertical section through the fan ring or housing, taken on the line l-i of Fig. and showing the fan proper in side elevation;

Fig. 2 is a view in elevation, looking from left 5 to right facing Fig. 1;

Fig. 3 is; a view in side elevation of a'fan housing containing a reversible type fan; Fig. 4 is a view in end or front elevation, looking from right to left facing Fig. 3, and Fig. 5 is a chart showing graphically the characteristics of the fans of Figs. 1 and 3. Referring to the drawings, Figs. 1 and 2, by characters of reference, the numeral i designates a fan housing preferably of sheet metal 5 and of rectangular external contour having a marginal surrounding flange 2 which serves to reeniorce the orifice plate 3. Extending from the inner periphery of the plate 8 in a direction opposite to flange 2 and in the direction of air flow,- there is a fan ring or shroud 4 or converging-diverging form defining the fan orifice and having its inlet end of greater internal diameter than its outlet end. The fan ring 6 is preferably formed as shown by a series of conic sections as ioined by conic sections and said sections preferably intersect tangentially. Positioned in the orifice, there is a fan proper 5 having radially and oppositely extending blades 8, I and which is mounted on the shaft f the driving motor .8 which is supported by the housing I.- The 5 blades 6, I are offset so that the width of the leading edge portions of each blade is greater 7 than the width of the trailing edge portion of that blade, the leading portions preferably being substantially twice as wide as the trailing poro tions. The leading edge portion of each blade is also preferably of greater radial length than its respective trailing edge portion so that the blades will cooperate with the fanrlng to overcome back suction. The radial length of the 1 blades on the line separating the leading and trailingedge portions of each blade and which is in the plane normal to the axis of rotation,

is slightly less than the minimum internal diameter or the throat diameter of the ring 4 so go that the tips 33 of the leading edge portion: of the blades act to discharge air against the converging, convexly curved inlet side of the tan ring I. As will be apparent from the drawings, Fig. l, the direction of lines of now of the air 25 stream discharging parallel to the fan axis of rotation will strike the internal converging ring surface 6 at a sharp acute included angle A, Fig. 1, of less than 45 fol-example, and preferably not more than 28 to 30, for to use a 3'0 larger included angle would result in a very material loss of power consumed in the abrupt changein the direction of air flow. The trailing edge portions iiand 25 extend beyond theplane of minimum diameter oi the ring 4 so 35 that the blades can exert a maximum eflort on the air stream. The portion ofthe plate 3 which extends around the orifice and at'rlght angles theretoserves to guide the air stream which is drawn'intc or enters the orifice] to maintain the a" lines of flow at the least angle of approach to the blades and to provide approximately uniform air velocity. The imaginary line separating the leading edge portions irom the trailingedge portions is shown'in the drawings by the line 45 x-x.

Themotor 9 is held in concentric relation to the ring I by radially extending supporting arms i0, preferably four in number and spaced equally about the motor shaft. Eacho! these arms is 5. rigidly fixed at oneend. as at H, to a supporting pad or reenforcing plate 12 whichis rigidlysecured as by bolts or in other suitable. manner to the corner portions of the plate 8 on the in- .let side of the fan housing. The arms it are u 11 7o ing a convex bent or curved so that their motor supporting ends lie in a common plane spaced from the inlet face of and parallel to the plane of the plate I. The motor supporting ends of the arms ii are flattened and bifurcated toprovide end slots in planes radial to the motor shaft. Positioned in these slots and rigidly secured to the arms are resilient supporting plates It. The plates II are rigidly clamped midway between 10 their ends in the end slots ll of the arms It by bolts ii. The opposite ends of the plates I; are received by fastening members It which are rigidly secured to the opposite end faces of the motor 8. It will thus be seen that the motor 9 is is rigidly held against movement radially or longitudinally of its shaft while being permitted a iimitedoscillatory movement about its shaft due to the resilience of the plates l3.

Referring to Figs. 3 and 4, the casing or hous ing 34 is of uniform internal contour with spaced,

inwardly converging, annular portions 3', 36 forming spaced throats with an internal, outwardly concave portion 31 forming a channel to receive the fan proper. Positioned within the housing 34, there is blades 38, 38 which are mounted on a driving shaft 40 supported in bearings ll carried by frame members 42. The diameter of the fan between the tips of blades ll and 3! is greater than the internal diameter of the throats and 38 so that on rotation of the blades in either direction, air will be forced against the internal conversing convexly curved inlet side or a surface of either the throat IS or the throat ll, 35 whichever is on the outlet side of the fan blades and thereby prevent back suction between the blade tips and the fan ring or housing. The blades ll and 38 are similar in external contour with the leading and trailing portions of 40 each blade being made symmetrical toeach other and of equal surface area so that the fan is reversible and can be rotated in either direction without change in efficiency of operation. The fan'ring housing 34 is preferably formed as shown by a series of conic sections joined by conic sections and said sections preferably intersect tangentially.

In Fig. 5, the curve a shows the power consumed in the movement of air by my fan as compared to the power to move the same volume of air by fans now on the market, as indicated by curve b. Curve c shows graphically the relation of volume of air discharged. relative to pressure by my fan as compared in curve d to the vol- .ume pressure characteristic of standard fans now on the market. From the curve c, it will be noted that my fan is capable of eillcient operation over the full range of air displacement whereas standard fans as shown by curve d have a limited range of efficient operation and that the volumetric displacement falls off considerably as the pressure against which they operate is increased. 7

This application is a division of my copending 65 application Serial No. 74,119, filed April 13, 1936,

for Fan, now Patent 2,126,599, dated Aug. 9, 1938. What I claim and desir .to secure by Letters Patent of the United States is:

l. A propeller fan comprising a fan ring havporting member concentric with said ring, fan blades carried by said supporting member and positioned on the inlet side of and within said 75 ring, the diameter of the circle defined by the fan blade tips being of greater length than the a fan comprising the internal face converging from its inlet side in the direction of fluid flow, a supminimum internal diameter of said ring and said blades-extending at their trailing edges through the plane of minimum diameter of said ring whereby the outer end portions of said blades act to force fluid obliquely against the'inlet side 5 of the convex ring surface thereby reducing back suction.

2. A reversible fan comprising a fan ring hav-- ing an internal face undulating in longitudinal cross-section defining inwardly convex circum- 10 ferential portions'and an intermediate outwardly concave circumferential portion, a propeller fan positioned in said ring and having its length be-- tween opposite blade tips of greater dimension than the minimum diameters of said convex por- 15 tions whereby the outer end portions of said blades act to force fluid against the inlet face of the convex portion on the outlet side of said fan thereby reducing back-suction.

3. A' propeller fan comprising a fan ring havo ing an inlet and an outlet and havlngan annular inlet section with its inner wall surface of convexly curved converging contour, supporting means concentric with the center line of fluid flow through said ring, fan blades extending ra- 25 dially from said supporting means and discharg in toward the plane of minimum diameter of said inlet section, the tips of said blades being positioned within said inlet section and extend-' ing beyond the circle of minimum diameter of 30 said inlet section so that the circumferential annular portion of the discharged fluid stream will impinge obliquely against the convexly curved wall surface.

4. A propeller fan comprising a fan ring hav- 35 ing an inlet and an outlet and having an annular inlet section with its inner wall surface of convexiy curved converging contour, supporting means concentric with the center line of fluid flow through said ring, fan blades extending-ra- 4o dially from said supporting means and discharging toward the plane of minimum diameter of said inlet section, the tips of said blades extending beyond the circle of minimum diameter of said inlet section so that an outer annular por- 45 tion of the discharged fluid stream will impinge obliquely against the convexly curved wall surface, said ring having an annular outlet section extending from said inlet section and of a diameter at least equal to the minimum diameter of 51) said inlet section thereby to eliminate substantially all eddy currents at said ring outlet. 5. A propeller fan comprising a fan ring having an inlet and an outlet and having an annular inlet section with its inner wall surface of con- 55 vexly curved converging contour, supporting means concentric with the center line of fluid flow through said ring. fan blades extending radially from said supporting means and discharging toward the plane of minimum diameter of said inlet section, the tips of said blades extending beyond the circle of minimum diameter of said inlet section so that an outer annular portion 'of the discharged fluid stream will impinge obliquely against the convexly curved wall surface. said ring having an annular outlet section with its inner wall surface of convexly curved diverging contour and extending from said inlet section thereby to eliminate substantially all eddy currents at said ring outlet.

having a wall surface surrounding said inlet and with the center line of fluid flow through said 1 ring, fan blades'extending radially from said supporting means and discharging toward the plane of minimum diameter of said inlet section, the tips of said blades extending beyond the=circle of minimum diameter of said inlet section so that an outer annular portion of the discharged fluid stream will impinge obliquely against the convexly curved wall surface.

'7. A propeller fan comprising a fan ring having a convex internal face converging from its inlet side in the direction of fluid flow, a supporting member concentric with said ring, fan blades carried by said supporting member and having leading and trailing surface portions intersecting on a line substantially in a plane normal to the direction of fluid flow, said leading portions being positioned on the inlet side of and having parts thereof within said ring, the circle defined by rotation oi the tips of said leading portions being of greater diameter than the minimum internal diameter of said ring, said normal plane being substantially at the minimum in-.

ternal diameter of said ring whereby the outer end portions oi said leading portions act to force fluid obliquely against the inlet side of the convex ring surface thereby reducing back suction, and whereby said trailing portions act on said fluid in the area of substantially greatest fluid velocity.

8. In combination, a propeller fan comprising leading and trailing surface portions, said portions intersecting in lines lying ina plane substantially perpendicular to the direction of air flow through said ian, and a shroud ring having an inlet and an outlet and comprising a series of conic sections joined together by other conic sections, said sections intersecting each other tangentially so as-to form a conduit member having a converging-diverging bore with a portion of minimum diameter, said fan trailing edge portion extending on the outlet side of said minimum diameter of said ring, and saidleading surface portions being on the inlet side of said minimum diameter of said ring.

9. In combination, a propeller fan comprising leading and trailing surface portions,- said portions intersecting in lines lying in a plane substantially perpendicular to the direction of air flow through said fan, and a shroud ring having an inlet and an outlet and comprising a series of conic sections Joined together by other conic sections, said sections intersecting each other tangentially so as to form a conduit member having a converging-diverging bore with a portion of minimum diameter, said leading edge portions defining by rotation of the tips thereof a circle of larger diameter than the minimum diameter of said ring, said defined circle being within said ring, said fan trailing edge portions extending on the outlet side of said minimum diameter of said ring, and said leading surface portions being on the inlet side of said minimum diameter of said ring. I

EDWARD LOWELL ANDERSON. 

